Circuit-control mechanism for internal-combustion engines



Jly 31, 1.9281. 1,679,159

L. C. FRENCH CIRCUIT CONTROL MECHANISM 4FOR INTERNAL COMBUSTION ENGINESFiled Feb. 23, 1927 2 Sheets-Sheet l July 311, 192g. 1,679,159

- L. O. FRENCH CIRCUIT CONTROL MECHANISM FOR INTERNAL COMBUSTION ENGINES'F'ii'ed Feb. 23, 1927- 2 Sheets-Sheet 2 a 25k; fwd@ Patented July 3l,1928.

UNITED STATES Pfrlarrr4 OFFICE.

Louis o. FRENCH, or MILWAUKEE, WISCONSIN.

Application filed February 23, 1927. Serial No. 170,328.

The invention relates to circuit control mechanism for electricalsystems for internal combustion engines, such as electrically Ycontrolled fuel injection systems or ignition 5 systems for suchengines.

In electrical systems heretofore proposed thecontrol of the current toan electromagnetically-operated fuel-metering device or the spark plugor other electrically-operated ignition device has been by a timer ofthe make-and-break type. Such timers are open to the objection of thepitting of the contacts through arcing and the consequent necessity forthe renewal of defective contacts and l5 accurate setting, and in someinstances the lrenewal of the parts on which t-hese-contacts [arecarried becauseJ of the difliculty of re- Lplacing the contacts4 in saidparts. One of ."t'lie objects of this invention is to provide a 2Oftimerwhich eliminates the use of contacts 'f'fby providing a variableresistance and enf Tine-controlled or engine-operated means for ivarying this resistance to control the opera- "tion of a fuel-meteringdevice of a fuel inyjection or supply system or the ignitor of theignition system of the engine.

This application is also a continuation in part of my prior'.application ISerial No. 99,325, filed April 2, 1926, for means forControlling fuel supply to internal combustion engines and also containssubject-matter divided from my copending application Serial No. 103,561,filed April 21, 1926, for fuel injection systems, as to the circuitarrangement, including a variable resistance timer and a distributor inthe same circuit.

Another object of this invention is to provide a control of the typedescribed for the 'fuel-metering device of a fuel injection systemwherein the control of the operating magnet for the metering device iseffected during the available injection period by a fluctuation ofcurrent flowing through said magnet during this period, the variableresistance being varied during the available injection period byengine-controlled means to effect the operation of said device at thedesired time or period in the engines cycle to thereby control theamount of fuel delivered to the engine. Since during the availableinjection period some current is flowing .through the-operating magnetand the current is then increased during this period, the time constantof the magnetic control circuit is reduced and thus the operation ofsaid magnet is very sensitive and suitable for high-speed engines.

A further object of the invention is to provide engine-controlledactuating mechanism for a variable resistance whereby either the time ofactive energization or the strength of such energization, or both ofthese, may be varied to control the electrically-operated device and inthe case of a fuel-metering device thus cause it to control the supplyof more or less fuel to the engine or to supply constant quantitv fuelchanges at different engine speeds.

The invention further consists in the several features hereinaftersetforth and more particularly defined by claims at the conclusionhereof.

In the drawings Fig. 1 is a view, partly in section, of' a circuitcontrol mechanism embodying the invention, parts being broken away, themechanism being shown as associated with a fuel-metering device of afuel injection system;

n Fig. 2 is a sectional view through the control mechanism, taken on theline 2-2 of Fig. 1

Fig. 3 is a top view of a timing cam;

Fig. 4 is a side elevation view of the` .timing cam shown in Fig. 3;

Fig. 5 is an end view of another timing cam;

' Fig. 6 is a detail View of a modified control mechanism;

Fig. 7 is a detail sectional view taken on the line 7-7 of Fig. 6;

Fig. 8 shows the circuit control mechanism and another circuitlarrangement for a fuel injection system;

Fig. 9 is a view, partly in section, of a circuit control mechanismembodying the invention, parts being broken away, the mechanism beingshown in an engine ignition system.

The timer or circuit control mechanism is a variable resistance orrheostat associated with the control circuit of the system lin which theresistance is periodically varied by engine-controlled means to causethe operation of the fuel-metering device or the ignition device duringthe desired or predetermined cyclic period and thus control theoperation of said device.

The variable resistance or rheostat may be i of any suitableconstruction though those of the compressible or pressure type, eitherusing disks or powdered resistance material, are preferred as theyrequire only a small movement to effect rapid changes in resistance andare not subject to appreciable wear. As illustrative of a variableresistance, I have shown in Figs. 1 and 2 a rheostatlO of the pressuredisk type wherein the" numeral 11 designates a casing of insulatingmaterial provided with side flanges 12 associated with the side flanges13 of a cover and guide plate 14, said flanges having --bolts 15'passing therethrough and clamping the device to posts 16 on thesupporting member 17, said bolts preferably being insulated from saidposts so that one of them may be usedas a terminalfora conductor 18. Aplurality of resist-ance disks 19, of carbon or any suitable resistancematerial or composition resistance 'matcrialare mounted in the casing 11between a metal terminal plate 2O and a pressure plate 21. The plate 20has i ,a' threaded terminal stud 22 projecting through the rear end ofthe casing and clamped thereto by nuts 23, one of which serves to clampa conductor 24 to said terminal. A thrust member 25, bearing against theplate 21, is slidably mounted in a guide bore in the plate l14 and has ahead 26 of insulating material faced with a metal plate 27 A spring 28is interposed between said head and plate 14 and normally acts to movesaid member 25 outwardly to a position where the plate 21 is exertinglittle if any pressure upon the disks 19, though current a is flowingtherethrough, so that a relatively large resistance is interposedbetween the terminals to impede the passage of the current from abattery 29 or other suitable source of current connected at one side tothe conductor 18 and having its other side grounded at 30.

The conductor 24 leads to one terminal of the operating coil 31 of theelectromagnetically-controlled fuel-meteringdevice, here shown asincluding a control valve 32, and

the other terminal of said coil is grounded,

at 33. i

While the metering device instanced here as a control valve 32 is shownherein for the purpose ofv illustration as a fuel injector' valve, Idesire it to' be understood that the present invention is not limited tothis ar rangement, as fuel regulation'may be obtained by having theelectromagneticallyoperated valve function as a suction or bypass valveof a pump, as a distributor valve inthe discharge line from a singlepump furnishing several cylinders with fuel, or as a valve in thedischarge line associated with a fuel injector valve.

The electromagnetic valve may be of any suitable construction and asinstanced here directly controls the passage of fuel through thedischarge nozzle 34 into the engine cylinder 35. As the features of thevalve shownhere have been made the subject of other applications, adetailed description thereof is not deemed necessary. However, the valveshown includes a core 36 having a fuel passage 37 extendingtherethrough, supplied with fuel from the discharge pipe 37 of the pump,an outer pole 38, a sealing gasket 39 of non-magnetic materialinterposed and clamped between the poles, a casing 40 of non-magneticmaterial having a chamber 41 communicating with the passage 37 in whichthe armature 42 ofthe valve works, a passage 43 connecting said chamberwith a chamber 44 adjacent the valve seat member 45, and a spring 46tending to close said valve through the fuel-pressure also tends toclose said valvewhere the valve is mounted in a pressure chamber.

In all of the instances above cited where the Acontrol valve may beused, the rheostat normally includes so much resistance in the circuitthat thecurrent flowing through the valve-controlling magnet isinsufficient to lift the valve, however, when lpressure is put upon thedisks 19 byl the inward movement of the stem 25 of the plunger enoughresistance is cut out of the circuit to permit the magnet to open thevalve and thus either establish a flow of fuel to the supply side of thefuel pump in the first instances cited of the suction or bypass'valve tothus control the amount of fuel supplied by the pump to the engine, andin the other instances cited control the passage of fuel in thedischarge line of the pump to the engine.

As a means for periodically varying the resistance, I have shown inFigs. 1 and 2 a shaft 47, either driven by the engine or operating incyclic synchronism therewith and having a timing cam 48 mounted thereon.While said cam may operate directly on the head 26 of the member 25, Iprefer to interpose a lever 49 between said parts pivoted at 50 andhaving a curved projection 51 engaging said cam and a pivoted roller 52engaging the wear plate 27.

This timing cam may have rotary motion alone so that as the speed of theengine increases the time during which resistance is cut out to permitthe valve to operate decreases, but I prefer to provide a greater rangeof adjusting the timing period and/o1' the amount of resistanceperiodically cut out of the control circuit by `providing a cam ofvarying contour movable relative to the projection 51.

In the timing cam shown in Figs. l and 2 the lift is constant and theduration of lift is varied as shown at 53, and in Figs. 3 and 4 the cam|54 has a 4surface providing a variable lift, or the cam may be shaped togive a combination of variable lift and variable duration of lift, asshown by the surface 56 of the cam 56 of Fig. 5. Any one of the abovedescribed cams may be mounted on the shaft 47 and by varying theposition of the cam relative to the lever 49 the operation of the member25 is varied, either by causing said plunger to exert pressure upon thedisks for varying periods of time, or to vary the pressure upon thedisks. 1Varying the period during which the resistance 1s cut out causesthe magnet to hold the valve open for longer or shorter periods of time;varying the amount of resistance cut out causes the magnet to vary thelift of the control valve. Hence in either instance the amount of fuelpassing by the valve may be varied, though it will be understood' thatwhere the control valve is associatedwith the supply side of the pumpthe period during which the valve is held open is the prime factor andthat the variable lift to the valve is more particularly of advantagewhere the valve is used in the discharge line from the pump.

As a means for varying the position of the timing cam relative to thelever 49 and member 25, I have shown in Fig. 2, a key 57 slidablymounted in a keyway in the shaft 47 and secured at one end to the lowerend of the cam 48 and at its other end to aI sleeve 58. This sleeve maybe manually opera-ted,`

a spring 59 acting to move it in one direction, or it may begovernor-operated.

The member 17 has a hub portion 17 rotatably mounted, for manualadjustment. to advance or retard the cutting out of resistance, in acasing 60, screws 61 being mounted in said casing and extending into anannular groove 62 in said hub portion to prevent relative longitudinalmovement of these parts.

For governor operation the sleeve 58 is slidably mounted in a sleeve orhub portion 63 of the governor spider which has a keyed connection 64E`with a shaft 65 driven by the engine. Levers GG are pivoted at 67 to thegovernor spider, their forked arms having pin projections 68 engaging inan annular groove G9 of the sleeve 58, their free ends carrying thegovernor weights 76. A collar 7l is slidably mounted on' the shaft 65and has an annular groove engaged byvprojections on the forked arms 72of ay lever pivoted at 72 and having an exteriorly disposedmanually-operable arm 73 whose downward movement effects an upwardmovement of the sleeves 63 and 58 compressing the spring 59 and therebyvarying the governors operating range and also permitting a manualshifting of the timingcam. As the speed of theengine increases the arms68 move the sleeve 58 upwardly and Ahence vary the position of thetiming cam and thus control the action of the resistance device, as prelviously pointed out.

Where an automatic advance or retard of the time of injection isdesired, and particularly where Such advance or retard of the time ofinjection has been predetermined to best suit the design of a particularengine, I have provided oppositely disposed slots 74 of varyingangularity, one being shown in full, with a pin 75 carried by the sleeve63 associated with each slot. Ihus, when the'sleeve 58 is moved by thegovernor it will -also turn or be moved angularly relative to the sleeve63 and shaft 65, and by its keyed connection with the shaft 47 cause asimilar angular movement of said shaft and hence an angular forward orbackward movement lof the cam. The shaft 47 is journalled in aball-hearing 76 mounted in the case 60 and has a shoulder 76 engagingthe inner race of said bearing to prevent its upward movement, and a`roller thrust bearing 77 is interposed between the lower end of saidshaft and the shaft 65. s

Thus, byshifting the cam 48 lengthwise, either by the manual operationof the lever 73 or by the shifting of the sleeve 58 by the governorduring the rotation of said cam 48, it willperiodically exert pressureupon the lever 49 and hence the resistance disks for varying periods oftime, and as the speed of rotation of the shaft 47 varies with the speedof the engine, such variations of timing period may, for a particularcam dcsign within a' given speed range, cause'a substantially constantactive period of valve magnet energization with a consequentsubstantially constant quantity of fuel charge, or said cam design maybe such as to cause a varyfng period of active energization of the valvemagnet with a consequent varying amount of fuel charge, generallydecreasing as the speed of the engine increases, and in either case whena predetermined maximum speed has been attained the cam is moved to aposition where the projection V5l rides on a part 48 where it is nolonger lifted by the cam and hence the resistance is not periodicallycut out and the control valve is rendered inoperative until the speed ofthe engine again drops below the maximum value. Under these 'conditionsfor any given period the lift of the valve is substantially constant.l/Vith the cam shown in Figs. 3 and 4 the lift or movement of the lever51 is varied and hence the amount of resistance cut out is varied fordifferent speeds and hence the lift ofthe fuel valve is varied and hencethe quantity of fuel supplied to the engine is varied. In Fig. 5,shifting of the cam varies both the dura` tion of thecutting-out-resistance period and the amount of resistance cut out toeither obtain constant quantity fuel charges at varying speeds or fuelcharges varying with the speed.

In Figs. 6 and 7 I have shown a resistance actuator designed to providea substantially constant time of diminished resistance period through awide range of engin@ speeds and thereafter a decreased time ofdiminished resistance above a predetermined speed and, finally, atmaximum speed the cutting out of the fuel supply by the failure of theactuator to cut out resistance, particularly where the control valve isin the pressure fuel discharge line. For this purpose lthe shaft 47 isprovided with a timing cam7 8 having a toothed lobe 79 engageable with aprojection on a member 81 carried by a curved spring 82 anchored atv 83to the support 17, the member 81 engageable with the insulated head 84of the thrust member or plunger 85 associated with the variableresistance device 10 so that as said cam rotates the member 85 is givena quick inward movement whose timing 1s substantially constant for awide range of engine speeds and hence the' resistance is periodicallydiminished for substantially equal periods and hence a constant quantitycharge of fuel is periodically furnished the engine at these speeds andthereafter said cam may be moved upwardly by a governor, similar to thegovernor previously described but' coming into operation only above apredetermined high speed, and through its association-with a key 86,similar to key 57, and a sleeve similar to the sleeve 58 causinganupward movement of the cam 78 to bring a tapered portion 87 into playand thus gradually decrease the extent of movement of the member 81, 82and the plunger 85,-and finally fail to operate said member 81, 82 andsaid plunger 85 and thus cut off the supply of fuel to the engine at apredetermined maximum speed.

The resistance device 10', shown in section in` Fig. 6, is also one thatI have used experimentally and has a finely powdered metallic resistancematerial 86 interposed between iianged metal disks 87, a spring 89 beinginterposed between one of said disks and a metal plate 90 engaged by theinner end of the plunger 85, and a spring 91 int-erposed between theother disk and a washer 92, all of these parts being mounted in a casing93` of insulating material, and the washer 92 being associated with theterminal screw 93.Y A'spring 96 may be mounted between annular feltwashers 97 to keep said spring out of contact with the disks 87 in thepowder-containing chamber so as to prevent any possibility of' thepacking of the powdered resistance material.

In Fig. 1 I have shown a 'hand-operated switch 94 in theconductor 18,and a manually-variable resistance 95 which permits the fuse of acertain iiXed resistance in the circuit that may be advisable in someinstances, and permits of varying this resistance to thereby7 modify theaction of the enginecontrolled resistance previously described.

While I have shown the apparatus in connectlon With a single cylinderengine, it will be understood that in a multicylinder engine a variableengine-controlled metering device control resistance may be associatedwith each cylinder, and that these may be connected in parallel with thesource of current and the resistance 95, and arranged, as many asconveniently possible, radially relative to a common timing cam oractuator. l

While the invention .has been described more particularly in connectionwith a fuel control valve, it is not, when broadly considered, to belimited to a valve, as the control means 'may be associated with anyother suitable fuel-metering device for the injection system of theengine.

It will be understood that, while the draw.- ings show a system usingdirect current, in case alternating current is used to operate themagnet that an engine-controlled variable resistance, either ohmic orinductive that is to say, a variable impedance, would be used to controlthe periodic operation of the electromagnetically-operated meteringdevice. i

In a multicylinder arrangement, instead of using a variable resistancefor each deviceI to be controlled I have shown in Fig. 8 a singlevariable resistance timing mechanismV 10, of thefirst-describedconstruction, connected by a conductor 96 to one side ofa battery 97 grounded on its other side at 98, a manual cut-out switch99 and a variable resistance. 100 being associated with said conductor,the resistance `100 serving to modify the action of the controlresistance 10. A conductor 101 connects the other terminal of theresistance timer 10 with a rotating brush 102, driven by the engine orrotated in cyclic synchronism therewith, of aaedistributor 103, saidbrush moving over a commutator including contact segments 104. Each ofthese contacts 102 is respectively connected to the coil of the controlelectromagnet of one of the fuel-metering devices by a conductor 105 andthe other terminal of -the coil is grounded at 106.

With this arrangement the cam 48 periodically acts to cut out resistancefrom the circuit and at such a time as it is desired to have themetering device function and while the brush 102 is in contact with onelos A lio of the contacts and under these conditions sufficiently tocause the metering member to operate.

Furthermore, the contacts 104 are preferably of such a length or thebrush 102 is of such a length that engagement takes place before the camt8 causes a cuttlng out 0f or change in current strength through the'variation of resistance under the action of v the increased resistanceand hence, when the current increases,by the cutting out of resistance,one of the contacts 104 and thebrush are already in contact so thatthere will be little, if any, arcing between the distributor brush andassociated contacts 104. With this construction, owing to the relativeproportions of the contacts and brush there is always some currentflowing through the operating magnet of the metering device durin periodso that w en the resistance is cut out by the cam 48 the current passingthrough the'magnet will rapidly reach the desired o erating strength.

Thus 'ar the circuit control mechanism has been described in connectionwith the metering control device of a fuel injection system but it willbe understood that instead of running the current through the magnet 31it may be passed through the primary winding of an induction c oil ofthe ignition system of the engine in which instance it is preferable touse a cam having a rapid drop, such as the cam 78, without a taper, sothat the rapid fluctuation the toothed projection 79 will createa rapidchange in linx inthe primary lwinding and hence induce a current ofhigher voltage in the usual secondary winding associated with the sparkplugs of the engine to cause said induced current to jump the sparkterminals and ignite the charge inthe engine.

As further illustrative of this usev ofthe timer I have shown in Fig. 9the variable resistance timer 108 associated with ahigh l tensionignition system of an internal combustion engine. As shown, this timerincludes a spring 109 which is interposed between a 'terminal plate 110and a metal-l plate 116 and enages the disk 113 and its `headed end isheld against a pin projection 120 on the outer end of a lever 121 by aspring 122, said lever being pivotally mounted onl a pin 123 secured tothe base plate and having a projection'intermediate its ends engaged bythe actuating cam. As shown, a projection\124 has spaced ears 125 (onebeing shown) through which a pivotpin 126 passes, said pin also passingthrough the lever121, which is preferably of chanthe availableinjection.

nel formation, with the pin passing through the flanges thereof. Thisprojection has an angle portion 1271 forming a stop, to limit itsswinging movement in one direction, engaged by a flat spring 128normally holding it in stop position and secured to the web -of thelever adjacentv its pivot. The projection 124 is disposed in the path ofthe operating cam 129 which has a toothed lobe 130 for each spark plugor as many lobes as can be satisfactorily used on one :cam and in thepresent instance I have `shown four lobes for a -four cylinder engine,

projection 124 is free to swing outwardly toward the outer end of thelever 121 and said lever is limited in its outward movement by astop-pin 121.

The inner end of the timer is grounded through metal parts, as at 132,and the outer end has a conductor 133 secured to its terminal andconnecting it with the primary coil or winding134 of an induction coil,the other end ofsaid winding being connected by a conductor 135 to oneside of a battery 136 whose other side is grounded at 137, saidconductor having a manually- )controlled cut-out switch 133 therein.

The secondary winding, 138 of the induction coll 1s grounded vatJ oneend 140 and "has its other end connected by conductor 141 with theengine-driven distributor brush 142\--Which engages, or is spaceda'short distance from, the contact segments 143 of theV distributor 144.Each segment 143 is respectively connected by a conductor 145 with oneterminal of a spark plug 146 whose other terminal is grounded.

With this construction the sp'ring 109 is relatively heavier than thespring 122 and the timer with its -lever 121 is so adjusted relative tothe stop pin 121 as to cause the spring109 to exert only a yslightpressure on the disks 112 so that a very small amount of current isflowing in the primary circuit until one of the lobes 130 of the cam 129engages Vthe projection 124 and lifts the lever 121 and hence putspressure on the disks 112 to provide for a considerably greater flow ofcurrent for a brief. interval and then a return to the smaller currentflow. As the strength ofthe current flow in the primary winding 134isthus changed rapidly from a full current ow to a very small amount, asfor instance, a small fractlonal part of an ampere, such change will setup a rapid change in flux in the magnetic ield of the induction coil andthus induce a'currentin the high voltage secondary Winging 138 at a timewhen the brush 142 is electrically associated with one of the contacts132 so that 4the high voltage current Will pass through ance isapplicable to either ignition or fuel injection systems though in suchlatter systems the abilit to change the relative difference between ighand low `current value isv made use of for varying the action vof thefuel-metering device to supply more or less fuel to the engine.

It will be noted that in thev forms shown the lever associated with thecam engages the thrust or ush-rod beyond the point of connection wi hthe cam so that a greater fluctuation of resistance is thereby obtainedthan could be obtained by direct action of the cani on said thrust orpush-rod.

Vos

I desire it to be understood that'this linv vention is not to be limitedto any particular form or arrangement of parts except in so far as suchlimitations are included 1n the claims or necessitated by the prior art.

What I claim as my invention is:

1. In a timer for internal combustion engines, the combination of avariable resistance, and engine-controlled means for periodicallyvarying said resistance.

2. In a timer for internal combustion engines, the combination of avariable resistance of the pressure type, and engine-operated means forperiodically varying said resistance.

3. In an internal combustion engine, a timing circuit comprising aclosed circuit, and engine-controlled means for periodically fluctuatingthe flow of current in said circuit. o

4. In a timer and circuit control mechanism for internal combustionengines, the combination of a variable resistance, a variable actuatorcontrolled by the engine for periodically varying said resistance, andlieans'for varying the action ofsaid actua or.

5. In a timer and circuit control mechanism for internal combustionengines, the combination of a Variable resistance, an engine-controlledtiming cam for ,periodically varying said resistance, said cam having avariable contour, and means for moving said cam and said resistancerelative to each other to vary the relative durationof the periodicchange of resistance. l

6. In a timer and circuit control mechan ism for internal combustionengines, the combination of a variable resistance, an engine-controlledtiming cam for periodically varying said resistance, said cam hav1ng avariableQ lift, and means for changing the position of said cam and saidresistance relative to each other to vary the amount of resistance cutout during a periodic-cutting out of resistance.

7. In a timer and circuit control mechanism for internal combustionengines, the combination of a variable resistance, an engine-controlledtiming cam for periodically var inosaid resistance, said cam having va.variab e lift associated with a variable duration of lift, and means forchanging the position of said cam and resistance relative to each`otherto vary the amount of resistance eriodically cut out and-therelative duration of the period during which such resistance is cutout.

8. In a timer for -internalcombustion engines, the combination of avariable resistance, an engine-operated timing lcam for 'periodicallyvarying said resistance, and a speed-responsive device associated withsaid cam to vary its'time of cutting out resistance.

' 9. In a timer for internal combustion engines, the combination of avariable resistance, an engine-controlled resistance actuator `toperiodically vary said resistance, and automatic means for advancing orretarding said actuator,

10. In any internal combustion engine, the combination of an electricalcontrol circuit including a variable resistance, means operating iniyclic synchronism with the engine for erio ically varying saidresistance, and

-anot er variable resistance in said circuit actuator to saidresistance.

12. In a fuel injection system, the combination with a plurality ofelectromagvnetically-controlled fuel-metering devices,

of a'current distributor forsaid devices, a variable resistanceassociated with said distributor and controlling thecontrolelectromagnets of said devices, and `engine-controlled means forperiodically varying said resistance to operate said devices.

18. In a timer and-control mechanism for internal combustion engines,the combination of a variable resistance, engine-driven means forperiodically varying said resistance to cause a periodic cutting out ofresistance for substantially constant cyclic periods through a Widerange of engine speed, and a speedresponsive device for varyingtheaction of said means above a predetermined speedand rendering saidmeans inoperative at a predetermined maximum speed.

14. In a timer for internal combustion e11- gines, the combination of aplurality of disks of resistance material, arranged in a column, aspring associated with one end of said column, a thrust memberassociated with the other end of said column, and engine-operated meansfor periodically reciprocating said thrust member to vary the pressureon said disks. -f

15. In a fuel injection system, the combination with anelectromagnetically con-` sistance to increase the current flow throughsaid magnet during the available injection period sufficient to operatesaid device.

Intestimony whereof, I afiX' my signature.

Louis o. FRENCH.

